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Composites of rice husk/wheat straw with pMDI resin and polypropylene
, Article Polymers and Polymer Composites ; Volume 15, Issue 8 , 2007 , Pages 619-626 ; 09673911 (ISSN) ; Dadbin, S ; Jahanbakhsh, J ; Janat Alipour, M ; Sharif University of Technology
Rapra Technology Ltd
2007
Abstract
The application of agricultural fibers for making particleboards has been studied in two types of composites: (i) type I particleboards were composites of wheat straw and rice husk fibers with polymeric methylene di-phenyl diisocyanate resin (pMDI) as a binder made by compression moulding; (ii) type II particleboards were composites of rice husk and polypropylene made by extrusion and injection moulding. In type I particleboards, the effects of varying the resin content and various combinations of wheat straw/rice husk fibers were investigated and characterised in terms of physical and mechanical properties of particle boards such as modulus of rupture, modulus of elasticity, compression...
GMR in multilayered nanowires electrodeposited in track-etched polyester and polycarbonate membranes
, Article Journal of Magnetism and Magnetic Materials ; Volume 308, Issue 1 , 2007 , Pages 35-39 ; 03048853 (ISSN) ; Southern, P ; Ghorbani, M ; Iraji zad, A ; Schwarzacher, W ; Sharif University of Technology
2007
Abstract
Commercially available track-etched polyester membranes were used as templates to electrodeposit Co-Ni-Cu/Cu multilayered nanowires, giving room-temperature current perpendicular to plane (CPP) giant magnetoresistance (GMR) values of up to ∼12%. In contrast to similar nanowires electrodeposited in track-etched polycarbonate membranes, the GMR obtained in multilayered nanowires electrodeposited in the polyester membranes increased with decreasing Cu-layer thickness tCu, for tCu in the 2-7 nm range, indicating a lack of ferromagnetic coupling through pinholes, etc. Transmission electron micrographs showed clear evidence for smooth, parallel layer interfaces in the nanowires. © 2006 Elsevier...
Hydrometallurgical treatment of tailings with high zinc content
, Article Hydrometallurgy ; Volume 82, Issue 1-2 , 2006 , Pages 54-62 ; 0304386X (ISSN) ; Rashchi, F ; Sadrnezhaad, S. K ; Sharif University of Technology
2006
Abstract
Zinc exists as smithsonite and hemimorphite in the lead flotation tailings from the Dandi mineral processing plant in north western Iran. In this research, zinc-rich tailings produced in the Dandi plant were characterized mineralogically and a leaching study was carried out to assess the effect of several parameters on the kinetics of zinc dissolution. Parameters studied included: sulfuric acid concentration, reaction time, temperature and slurry density. It was found that leaching is controlled by a single rate-controlling step with an activation energy of 23.5 kJ/mol. To overcome some of the filtration problems associated with polymerization of silicic acid, lime was added as a coagulant....
Thermal degradation behavior and kinetic analysis of ultra high molecular weight polyethylene based multi-walled carbon nanotube nanocomposites prepared via in-situ polymerization
, Article Journal of Macromolecular Science, Part A: Pure and Applied Chemistry ; Volume 49, Issue 9 , 2012 , Pages 749-757 ; 10601325 (ISSN) ; Saadatabadi, A. R ; Khorasheh, F ; Sharif University of Technology
T&F
2012
Abstract
Thermal degradation behavior of multi-wall carbon nanotubes (MWCNTs)/ultra high molecular weight polyethylene (UHMWPE) nanocomposites, with different nanotubes contents (0.5, 1.5 and 3.5 wt%) prepared via in-situ polymerization technique have been investigated using thermal gravimetric analysis (TGA). TGA spectra revealed that these nanocomposites had enhanced thermal stability and no significant mass loss (<0.4 wt%) occurred up to 350°C. Thermal degradation of these UHMWPE/MWCNT nanocomposites was investigated in terms of parameters such as the onset temperature of degradation (T 10), the decomposition temperature at 50% wt loss (T 50), the degradation temperature of maximum rate of the...
Simulation and experimental evaluation of initiator and surfactant concentrations and temperature effects on styrene conversion and polymer particle size distribution in batch emulsion polymerization
, Article Iranian Polymer Journal (English Edition) ; Volume 19, Issue 8 , Aug , 2010 , Pages 599-614 ; 10261265 (ISSN) ; Shahrokhi, M ; Sharif University of Technology
Abstract
Effects of initiator and surfactant concentrations and temperature on styrene conversion and polymer particle size distribution (PSD) in a batch emulsion polymerization are investigated through simulation and experimental studies. The detailed model based on population balance (zero-one model), accounting for nucleation, growth and coagulation phenomena has been used for prediction of particle size distribution. In checking the effect of initiator concentration on final PSD, it was noticed that when critical micelle concentration (CMC) is kept constant, the model cannot predict PSD very well. Thus, a correlation for calculating critical micelle concentration has been proposed and...
Nanostructured particles for controlled polymer release in enhanced oil recovery
, Article Energy Technology ; Volume 4, Issue 9 , 2016 , Pages 1035-1046 ; 21944288 (ISSN) ; Ramazani S., A ; Shaban, M ; Ayatollahi, S ; de la Cal, J. C ; Sheng, J. J ; Tomovska, R ; Sharif University of Technology
Wiley-VCH Verlag
2016
Abstract
With the decline in oil discoveries over recent decades, it is believed that enhanced oil recovery (EOR) technologies will play a key role to meet energy demand in the coming years. Polymer flooding is used commonly worldwide as an EOR process. In this work, we propose the synthesis of protected polyacrylamide (PAM) nanoparticles (PPNs) with a hydrophobic polystyrene (PSt) shell by one-pot two-step inverse emulsion polymerization, in which the PSt shell was created by surface polymerization. The shell protects the active PAM chains from premature degradation caused by the harsh environment in the reservoirs, controls the release of the chains as rheological modifiers, and additionally, it...
High molecular weight polyacrylamide nanoparticles prepared by inverse emulsion polymerization: reaction conditions-properties relationships
, Article Colloid and Polymer Science ; Volume 294, Issue 3 , 2016 , Pages 513-525 ; 0303402X (ISSN) ; Ramazani S. A ; Shaban, M ; Ayatollahi, S ; Tomovska, R ; Sharif University of Technology
Springer Verlag
2016
Abstract
High molecular weight polyacrylamide (PAM) nanoparticle dispersions are products with wide application possibilities, the most important of which is in petroleum industry such as drilling fluid and flooding agent in enhanced oil recovery. For that aim, it is necessary to achieve complete control of the final dispersion and polymer properties during the synthesis step. In this work, PAMs were synthesized by inverse emulsion polymerization of aqueous acrylamide solution in cyclohexane in the presence of emulsifier mixture of Span 20 and Span 80. We present a comprehensive study of the effects of variation of all important reaction conditions (agitation rate, reaction time and temperature,...
Kinetic and morphological study of a magnesium ethoxide-based Ziegler-Natta catalyst for propylene polymerization
, Article Polymer International ; Volume 58, Issue 1 , 2009 , Pages 40-45 ; 09598103 (ISSN) ; Ramazani Saadatabadi, A ; Hiraoka, Y ; Kim, S. Y ; Taniike, T ; Terano, M ; Sharif University of Technology
2009
Abstract
Background: Kinetic andmorphological aspects of slurry propylene polymerization using a MgCl2-supported Ziegler-Natta catalyst synthesized from a Mg(OEt)2 precursor are investigated in comparison with a ball-milled Ziegler-Natta catalyst. Results: The two types of catalyst show completely different polymerization profiles: mild activation and long-standing activity with good replication of the catalyst particles for the Mg(OEt)2-based catalyst, and rapid activation and deactivation with severe fragmentation of the catalyst particles for the ball-milled catalyst. The observed differences are discussed in relation to spatial distribution of TiCl4 on the outermost part and inside of the...
Optimal control of molecular weight and particle size distributions in a batch suspension polymerization reactor
, Article Iranian Polymer Journal (English Edition) ; Volume 28, Issue 9 , 2019 , Pages 735-745 ; 10261265 (ISSN) ; Shahrokhi, M ; Farahzadi, H ; Sharif University of Technology
Springer London
2019
Abstract
Mechanistic modelling is an engineering approach to simulate reasonable physical and chemical processes to develop a model to describe the behaviour of a system. Mathematical models are commonly adopted to explore the physical limits of a process, and are applied to process development, optimization and control. In this work, the population balance model and the moment technique have been utilized to model a suspension polymerization reactor and predict the dynamic evolution of particle size and molecular weight distributions. These distributions are two important factors that affect the physical, rheological and mechanical properties of a polymer, and its final product quality. The cell...
Surface modification of polysulfone ultrafiltration membranes by free radical graft polymerization of acrylic acid using response surface methodology
, Article Journal of Polymer Research ; Volume 26, Issue 9 , 2019 ; 10229760 (ISSN) ; Asadollahi, M ; Mousavi, S. A ; Bastani, D ; Aghaeifard, F ; Sharif University of Technology
Springer Netherlands
2019
Abstract
In this research, polysulfone (PSf) ultrafiltration (UF) membranes were prepared by a phase inversion method. Surface modification of the PSf membranes was carried out via grafting of acrylic acid as a hydrophilic monomer by free radical graft polymerization initiated by redox reaction. A central composite design (CCD) of response surface methodology (RSM) was applied to design the experiments. The process variables were acrylic acid concentration (CAA), redox system contact time (T1), and acrylic acid polymerization time (T2), while the contact angle (CA), pure water flux (PWF), and flux recovery ratio (FRR) were considered as the responses. Analysis of variance (ANOVA) demonstrated that...
Improvement of performance and fouling resistance of polyamide reverse osmosis membranes using acrylamide and TiO2 nanoparticles under UV irradiation for water desalination
, Article Journal of Applied Polymer Science ; Volume 137, Issue 11 , 2020 ; Bastani, D ; Mousavi, S. A ; Heydari, H ; Vaghar Mousavi, D ; Sharif University of Technology
John Wiley and Sons Inc
2020
Abstract
The purpose of this research is to explain the surface modification of fabricated polyamide reverse osmosis (RO) membranes using UV-initiated graft polymerization at different irradiation times (15, 30, 60, and 90 s) and various acrylamide concentrations (10, 20, and 30 g L−1). Also, coating of membranes surface with various concentrations of TiO2 nanoparticles (10, 20, 30, and 50 ppm) followed by the same UV irradiation times was investigated. After that, the membranes modification was done by grafting of acrylamide blended with TiO2 nanoparticles via UV irradiation. The characterization of membranes surface properties and their performance were systematically carried out. The results...
A hybrid nanocomposite of poly(styrene-methyl methacrylate- acrylic acid) /clay as a novel rheology-improvement additive for drilling fluids
, Article Journal of Polymer Research ; Volume 26, Issue 2 , 2019 ; 10229760 (ISSN) ; Ghorbani, H ; Wood, D. A ; Abdollahi Khoshmardan, M ; Sharif University of Technology
Springer Netherlands
2019
Abstract
The hybrid-polymer nanocomposite poly(styrene-methyl methacrylate- acrylic acid) /nanoclay was synthesized by miniemulsion polymerization for novel use as a drilling fluid additive. Three low-solid-drilling fluids (bentonite-based; natural polymer-based; nanoclay-based) were formulated using the hybrid nanocomposite as an additive and their rheological performance compared. The polymer/clay hybrid nanoparticles significantly improve rheological and filtration properties of the drilling fluids and they remain stable at high pressure, high temperature and harsh salinity conditions. The fluids’ filtration properties improve as the concentration of the polymer/nanoclay-hybrid-nanoparticles...
Cobalt -mediated radical polymerization of vinyl acetate in a packed column system: simultaneous effective control of molecular weight, separation, and purification
, Article Journal of Polymer Research ; Volume 29, Issue 12 , 2022 ; 10229760 (ISSN) ; Dadkhah, A. S ; Kohestanian, M ; Mahdieh, A ; Semsarzadeh, M. A ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
The simultaneous control of the molecular weight, separation, and purification of polyvinyl acetate was achieved using a cobalt-mediated radical polymerization (CMRP) in a packed column with silica gel particles (PC-CMRP). The controlled radical polymerization of VAc in the packed columns was evaluated from the linear time dependence of Ln[M]0/[M], linear increase of molecular weight with the increase in conversion, and narrow molecular weight distribution. PC-CMRP method was used to produce high-purity polymers with controlled molecular weight and narrow molecular weight distribution without requiring additional purification steps. The high ability of silica gel particles to adsorb free...
Preparation of ultrahigh-molecular-weight polyethylene/carbon nanotube nanocomposites with a Ziegler-Natta catalytic system and investigation of their thermal and mechanical properties
, Article Journal of Applied Polymer Science ; Volume 125, Issue SUPPL. 1 , 2012 , Pages E453-E461 ; 00218995 (ISSN) ; Ramazani, S. A. A ; Izadi, H ; Sharif University of Technology
Wiley
2012
Abstract
In this research, ultrahigh-molecular-weight polyethylene (UHMWPE)/multiwalled carbon nanotube (MWCNT) nanocomposites with different nanotube concentrations (0.5, 1.5, 2.5, and 3.5 wt %) were prepared via in situ polymerization with a novel, bisupported Ziegler-Natta catalytic system. Magnesium ethoxide [Mg(OEt) 2] and surface-functionalized MWCNTs were used as the support of the catalyst. Titanium tetrachloride (TiCl 4) accompanied by triethylaluminum constituted the Ziegler-Natta catalytic system. Preparation of the catalyst and the polymerization were carried out in the slurry phase under an argon atmosphere. Support of the catalyst on the MWCNTs was investigated with Fourier transform...
Modified chitosan as a polymeric nanoreactor for fabrication of pure zno nano particles
, Article Journal of Applied Polymer Science ; Volume 117, Issue 2 , March , 2010 , Pages 1035-1040 ; 00218995 (ISSN) ; Barzegar, S ; Pourjavadi, A ; Sharif University of Technology
2010
Abstract
ZnO nanoparticles have been prepared successfully by hydrogel decomposition method (HDM). Synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD), fourier transforms infrared spectroscopy (FTIR), and transition electron microscopy (TEM) techniques. Narrow distribution of sizes with a 20-30 nm diameter and regular distribution of ZnO nanoparticles are attributed to the application of poly(acrylic acid-co-acrylamide) grafted chitosan hydrogel as coating agent. The results show that the polymer thermal decomposition technique is a perfect method for the synthesis of ZnO nano particles
PH-Sensitive stimulus-responsive nanocarriers for targeted delivery of therapeutic agents
, Article Wiley Interdisciplinary Reviews: Nanomedicine and Nanobiotechnology ; Volume 8, Issue 5 , 2016 , Pages 696-716 ; 19395116 (ISSN) ; Eslami, M ; Sahandi Zangabad, P ; Mirab, F ; Farajisafiloo, N ; Shafaei, Z ; Ghosh, D ; Bozorgomid, M ; Dashkhaneh, F ; Hamblin, M. R ; Sharif University of Technology
Wiley-Blackwell
2016
Abstract
In recent years miscellaneous smart micro/nanosystems that respond to various exogenous/endogenous stimuli including temperature, magnetic/electric field, mechanical force, ultrasound/light irradiation, redox potentials, and biomolecule concentration have been developed for targeted delivery and release of encapsulated therapeutic agents such as drugs, genes, proteins, and metal ions specifically at their required site of action. Owing to physiological differences between malignant and normal cells, or between tumors and normal tissues, pH-sensitive nanosystems represent promising smart delivery vehicles for transport and delivery of anticancer agents. Furthermore, pH-sensitive systems...
Effect of exfoliated molybdenum disulfide oxide on friction and wear properties of ultra high molecular weight polyethylene
, Article Polymers for Advanced Technologies ; Volume 29, Issue 12 , 2018 , Pages 3085-3096 ; 10427147 (ISSN) ; Ramazani S. A., A ; Afkhami Varjouy, A ; Faghihi, M ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
The aim of this work is to investigate the effect of molybdenum disulfide on tribological properties of Ultra-high-molecular-weight polyethylene (UHMWPE). UHMWPE/MoS2 nano-composites were prepared using in-situ polymerization and Ziegler-Natta catalytic system. Studies showed that, in order to obtain the optimum tribological properties, interlayer distance between nanosheets should be as high as possible. Therefore, the nanosheets were subjected to oxidation using the required oxidants followed by thermal shock and ultrasound. Fourier-transform infrared spectroscopy (FTIR) analysis was used to determine the formation of functional groups which indicate the formation of S═O bond in the...
Fuzzy Predictive Control of a Continuous Polymerization Stirred Tank Reactor
,
M.Sc. Thesis
Sharif University of Technology
;
Pishvaie, Mahmoud Reza
(Supervisor)
Abstract
In industries there are many nonlinear processes which cannot be easily controlled with classical methods. Model predictive control is a useful method for nonlinear processes which not only has high efficiency, but also extension of this control to interferential multi variable case, with constraint on the controlled and manipulated variables and other problematic dynamic specifications such as slow dynamics and inverse response is very simple. Industrial polymerization processes are regarded as significant nonlinear processes. Optimization and control of polymerization reactors have considerable importance in process applicability and in economics. The molecular structure of polymer such as...
Investigation Properties of Polypropylene/Carbon Nanotube Nanocomposites Prepared via in Situ Polymerization Using Bi-Supported Ziegler Natta Catalyst
, M.Sc. Thesis Sharif University of Technology ; Ramezani Saadatabadi, Ahmad (Supervisor)
Abstract
In this research polypropylene/carbon nanotube nano composites were prepared via in situ polymerization using Bi-supported Ziegler-Natta catalytic systems. Magnesium etoxide and Multi wall carbon nanotubes(MWCNT) functionalized by hydroxyl groups were used as supports of catalyst. TiCl4 and TiBA were used as catalyst and co catalyst respectively. After defining the polymerization optimum conditions and considering its parameters constant, nano composites with different carbon nanotube contents were produced by changing the polymerization time. Scanning Electron Microscopy (SEM) images certified very good dispersion of MWCNTs throughout polypropylene matrix. The thermal properties behavior of...
Fluids Flow Simulation in the Cell Influenced the Focal Adhesions
, Ph.D. Dissertation Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; saidi, Mohammad said (Co-Advisor)
Abstract
In the present thesis, intracellular fluid flows have investigated for study cell motions. It is due to firmly relation between the cell motion and these flows. Generally, the cell firstly adheres to a surface, then, moves forward with the effects of the internal fluid flows. In this study, the cell structure is invided to two general parts; the front part of the cell and the cell body. The front part of the cell plays a essential roles in the cell motion, however, the cell body is considered as a extra cargo that is carried by the front of the cell. Therefor, in the present modellings, the front part is only considered. Here, using four different models for the front part of the cell, many...